The present invention relates to a camshaft driving arrangement for a V-type double overhead camshaft (DOHC) engine.
Japanese Patent Publication No. 59-74312 (=U.S. Pat. No. 4,553,473) discloses a camshaft driving arrangement of the prior art as shown in FIG. 5.
Referring to FIG. 5, there is shown a V-type DOHC engine which includes a cylinder block 1, two cylinder heads 7A and 7B, and a crankshaft 2. Rotatably mounted to the two cylinder heads 7A and 7B are two idler gears 4 and two pairs of camshafts 9 and 10. Each of the two idler gears 4 includes a relatively small diameter gear 4a and a relatively large diameter gear 4b. Rotation of the crankshaft 2 is transmitted to the relatively large gears 4b through a belt B, causing rotation of the relatively small gears 4a. Subsequently, the rotation of each of the small gears 4a is transmitted to one of the two pairs of camshafts 9 and 10.
With such conventional camshaft driving arrangement, bowever, since an idler gear T and a tensioner 16 are arranged in the middle of an end face of the cylinder block 1 so as to stabilize or ensure an engagement of the belt B, the problem is encountered such that a space surrounded by the belt B is so small that an auxiliary device or an accessory such as a water pump cannot be disposed therein, resulting in an increase in the overall dimension of the engine.
An object of the present invention is to provide an effective solution of such problem by modifying a location of an idler gear and to provide a camshaft driving arrangement for a V-type DOHC engine which makes much contribution to a reduction in engine overall dimension and an increase in space for installing an auxiliary device.